Abstract

OBJECTIVE:

To investigate the impact of tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) upon immunological recovery and the T-cell compartment after initiation of TB and antiretroviral therapy (ART).

DESIGN AND METHODS:

We prospectively evaluated T-cell immunophenotypes by flow cytometry and cytokines by Luminex assays in a subset (n = 154) of highly immunosuppressed HIV-infected patients with TB from the Cambodian Early versus Late Introduction of Antiretrovirals randomized clinical trial. We compared findings from patients who developed TB-IRIS with findings from patients who did not develop TB-IRIS. Data were evaluated with mixed-effect linear regression, Kaplan-Meier estimates, and Wilcoxon rank-sum tests, and q-values were calculated to control for multiple comparisons.

CONCLUSIONS:

A distinct pattern of pre-ART T-cell and cytokine markers appear to poise the immune response of certain patients to develop TB-IRIS. Experience of TB-IRIS is then associated with long-term remodeling of the CD4 T-cell memory compartment towards an effector memory-dominated phenotype. We speculate that these pre and post-ART TB-IRIS-associated immune parameters may contribute to superior immune control of TB/HIV co-infection and better clinical outcome.

A. Flow chart of CAMELIA patient recruitment for the CAPRI-T sub-study. Of the 188 CAMELIA patients who provided informed consent for participation in the CAPRI-T study, 13 were excluded for the reasons shown in the figure, and an additional 21 were excluded after initial suspicion of TB-IRIS, which was not subsequently clinically validated.B. Schema showing how the CAPRI-T sub-study was nested within the CAMELIA clinical trial and the timing of blood samples relative to initiation of TB treatment and ART. The week 2 post-ART blood collection timepoint in the early and late CAMELIA treatment arms is indicated in the figure.

Markers of CD4+ and CD8+ T cell activation and regulatory activity in TB-IRIS and non-TB-IRIS patients

T cell immunophenotypes were obtained on whole blood samples. Lines depict mean progression over time deduced from mixed effect linear regression models in each patient group for the T cell subset shown. TB-IRIS patients (filled circles and solid line) and non-TB-IRIS patients (open circles and dashed line) are shown at the actual time of sample analysis post-ART initiation. Significant differences obtained from regression analysis in the frequency of each T cell subset at week 0 of ART and/or its rate of change post-ART initiation are indicated in each figure (see for full list of p- and q-values). NS= not significant; up arrow = higher in TB-IRIS; down arrow = lower in TB-IRIS. For CCR5+CD4+ T cells and CD4+ Tregs, regression plots were generated with square root transformation due to non-normal distribution. A) Activated (CD45RO+HLA-DR+) CD4+ T cells; B) CCR5+CD4+ T cells; C) Activated (CD38+HLA-DR+) CD8+ T cells; D) CD4+ regulatory T cells. So the spread of values in each subgroup (TB-IRIS vs. non-TB-IRIS) can be better appreciated, the two patient groups are shown immediately adjacent to one another at weeks 0, 2, 6, 8, 26, and 32 post-ART in .

OX40+CD4+ T cell frequencies were measured in whole blood samples. Lines depict mean progression over time deduced from mixed effect linear regression models. TB-IRIS patients (filled circles and solid line) and non-TB-IRIS patients (open circles and dashed line) are shown at the actual time of sample analysis post-ART initiation in the left panel. Significant differences obtained from regression analysis in the frequency of OX40+CD4+ T cells at week 0 of ART and/or its rate of change post-ART initiation are indicated (see for full list of p- and q-values). Up arrow = higher in TB-IRIS; down arrow = lower in TB-IRIS. Since OX40+CD4+ T cell frequencies were not normally distributed they were plotted using square root transformation. So the spread of values in each subgroup (TB-IRIS vs. non-TB-IRIS) can be better appreciated, the two patient groups are shown immediately adjacent to one another at weeks 0, 2, 6, 8, 26, and 32 post-ART in .B. Plot depicting Kaplan–Meier estimates for probability of developing TBIRIS depending on pre-ART frequency of OX40+CD4+ T cells. Black line: patients with >7.4% OX40+CD4+ T cells at ART initiation; grey line: patients with ≤ 7.4% OX40+CD4+ T cells at ART initiation.